1. Field of the Invention
Exemplary embodiments of the present invention relate to a method of inspecting a solder joint. More particularly, exemplary embodiments of the present invention relate to a method of inspecting a solder joint through which a lead of a semiconductor device is mounted on a printed circuit board (PCB).
2. Discussion of the Background
Generally, the solder joint, through which a lead of a semiconductor device is mounted on a printed circuit board, is inspected through the color of light captured by a camera, while irradiating RGB (red, green and blue) lights by RGB illuminators with different angles, respectively onto the solder joint.
FIGS. 1A and 1B are a cross-sectional view for explaining a conventional method of inspecting a solder joint.
Referring to FIGS. 1A and 1B, the RGB illuminators 210, 220 and 230 are arranged in clockwise direction over a solder joint 240 to irradiate RGB lights onto the solder joint 240 through the RGB illuminators 210, 220 and 230, respectively. Then, the solder joint 240 is inspected by determining color of light captured by a camera 250 disposed over the solder joint 240.
In detail, when the solder joint 240 is good as shown in FIG. 1A, the solder joint 240 is formed to have slant surface decreasing height from the end portion of the lead 260. Therefore, the blue light illuminated by the B illuminator 230 is captured by the camera 250.
On the other hand, when the solder joint 240 is defective such as no solder or cold solder as shown in FIG. 1B, the solder joint is not formed at the end portion of the lead 260 and the solder has relatively flat surface. Therefore, the red light illuminated by the R illuminator 210 is captured by the camera 250.
However, according to the conventional method of inspecting solder joint, using the RGB illuminators 210, 220 and 230, reliability of inspection may be lowered due to the interference of environmental light and the interference of adjacent elements.